Warren was originally the fishing schooner Hawk, probably built at Marblehead, Massachusetts, and owned by John Twisdon at the time of her appraisal for naval service in the American Revolutionary War by Colonel Jonathan Glover and Edward Fettyplace on 12 October 1775.

Bound from Lisbon, Portugal, to New York City with 153 quarter casks of wine, Sally had been captured by the fifth-rate HMS Niger earlier in the month, placed under a prize crew, and ordered taken to Boston.

After another rent and recruiting new crewmen, Warren joined schooners Lynch and Lee in an attempt to get to sea on 27 May 1776, but that day they could not slip past the British 28-gun frigate HMS Milford patrolling outside Cape Ann harbor.

In June 1776, she tangled with the British troopship Unity, bound for Halifax, Nova Scotia, with Hessian troops embarked, but met with a hot reception from the troopers' carriage guns and musket fire.

Returning to Beverly for repairs, Warren, still under the luckless Burke, put to sea again in late August 1776 to patrol the supply lanes between Nova Scotia and Boston.